A system for setting cervical vertebrae from behind

Abstract: Hooks (10) and plates (12) are used together with a number of jointed segments or cylinders (1) crossed longitudinally and vertically by a web (4) housing a connecting wire (8) that can be tightened with tightening means and locked by a screw (7) lying crosswise to each segment (1). The system can be used to join all the required levels; neither the point of insertion of the screws nor the position of the hooks are predetermined; and it can be used after laminectomy.

Description: The present invention relates to a system for setting cervical vertebrae from behind providing, in addition to the function for which it has been conceived, a number of advantages that shall be explained hereinafter and others that are inherent in its layout and construction. Several systems designed specifically to set the cervical column from behind are currently known. The said conventional systems, being a part of the prior art, could be divided into five types listed below: Wires passing through holes made on the rear arch of each vertebra to be fixed that are then knotted to form a lacing that joins the vertebrae to one another. It is inconvenient in that the resulting set is not sufficiently solid, and if the wires are passed beneath the laminae manipulation can prove dangerous. Longitudinal bars joined to the vertebrae by means of wires passing beneath the rear arch laminae and then knotted around the bar. It is inconvenient in that the wires must pass beneath the laminae, and this is dangerous. Hooks catching hold of the vertebral laminae and then joined to each other by bars or screws. The Halifax system is inconvenient in that it is only useful to join two levels. The bar and hook system can only catch hold of the two end vertebrae and not the intermediate vertebrae. They cannot be used after laminectomy. Plates fixed to the vertebrae with screws that catch hold of the articular mass of each vertebra. It is inconvenient in that the place, being rigid, prefigures and conditions the place at which screws are inserted. The Magerl system combines the previous two systems and has a sublaminar hook and a plate joined to the hook that is screwed to one or two articular masses. It is inconvenient in that, being a rigid part, the position of the screws is prefigured and is further only useful to join two or three levels. The Applicant has used his experience in the medical science subject hereof to design a new system for setting the cervical vertebrae from behind which conveniently overcomes the drawbacks that are usually found in the prior art methods succinctly described in the above section, now using hooks and plates and a number of jointed segments or cylinders crossed longitudinally and vertically to together establish a web housing a connecting wire that can be tightened and locked by a screw lying crosswise to the segment. Hence, the invention concerns a system for setting cervical vertebrae from behind, characterized in comprising (a) a group of distinct solid metal cylinders (1, 1a), said cylinders (1, 1a) having a stem of round cross-section and one of two possible heights, the top end of said cyclinders (1, 1a) being a hemisphere (2) having a diameter of 0.5 mm less than the diameter of the cross-section of said cylinders (1, 1a), whereas the lower end of said cylinders (1, 1a) is scooped to form a hemispherical cavity (3) whose internal diameter is 0.5 mm less than that of the cross-section of said cylinders (1, 1a) in order that the top protruding end (2) of one of said cylinders (1, 1a) may be precisely coupled to and turn within the lower scooped end (3) of another of said cylinders (1, 1a); (b) said cylinders (1, 1a) having an axial circular bore (4) having a calibre of 2 mm, said axial circular bore (4) opening at the top and bottom ends of said cylinders (1, 1a) forming an internal duct, the top opening of said axial circular bore (4) being surrounded by four holes (5), said four holes (5) being arranged at the ends of a virtual cross, with connecting lines each being 4 mm long, and said top opening being at the intersection of said connecting lines; and (c) the cylinder stem having at its longitudinal midpoint a threaded bore (6) with a calibre of 1.5 mm, said threaded bore (6) reaching the internal duct, said duct in the cylinders (1, 1a) allowing a number of said cylinders (1, 1a) to be strung by means of a braided wire (18), to form a structural assembly suited to the anatomic demands of the patient's vertebral morphology and size, the assembly being capable of being stiffened by tightening the said wire (18) using a wire tightening means, which couples the top and bottom ends of each of said cylinders (1, 1a); (d) the final structure of the assembly being consolidated by setting each of said cylinders (1, 1a) one by one onto said wire (18), using small screws (7) inserted in the said threaded bore (6) provided in the stem of each of said cylinders (1, 1a), said screws (7) compressing the wire (18) in the internal duct, thereby preventing said cylinders (1, 1a) from slipping. In a preferred system of the invention, one of said cylinders (1) having the larger height is 8 mm high, measured from the top end of said hemisphere (2) to the perimeter of said hemispheral cavity (3), and has a diameter of 5 mm, whereas another of said cylinders (1a) having the lower height is 4 mm high and has a diameter of 5 mm. It is also preferred in accordance with the invention that one of said cylinders (1) having the larger height is a cylinder selected from (a) one of said cylinders (1); (b) one of said cylinders (1), additionally comprising a downward hook (10) projecting from the upper half of a side wall of the cylinder body at an upwardly open 45 ° angle to the longitudinal axis of the cylinder (1) and bending down until its final portion is parallel to the longitudinal axis of said cylinder (1); (c) one of said cylinders (1), additionally comprising an upward hook (11) projecting from the lower half of a side wall of the cylinder body at a downwardly open 45° angle to the longitudinal axis of the cylinder (1) and bending up until its final portion is parallel to the longitudinal axis of said cylinder (1); and (d) one of said cylinders (1), additionally comprising an articular screw plate (12) of trapeziodal shape projecting from a side wall of the cylinder body at the major axis plane of the cylinder (1) with a length of 15 mm and having the same heigth as the cylinder stem on the side adjacent to the cylinder (1) and a heigth of 8 mm on the side remote from the cylinder (1). In an advantageous manner, the cylinder (1) having a downward hook (10) comprises the hook (10) as a 5 mm wide strip, and said threaded bore (6) for inserting said screws (7) is located on the side of said cylinder (1) diametrically opposite to the side from which the hook (10) projects. In another advantageous embodiment, the cylinder (1) having an upward hook (11) comprises the hook (11) as a 5 mm wide strip, and said threaded bore (6) for inserting said screws (7) is located on the side of said cylinder (1) diametrically opposite to the side from which the hook (11) projects. It is also an advantageous embodiment of the system that the cylinder (1) having an articular screw plate (12) has said plate (12) pierced by a hole (13) having a diameter of 3 mm, said hole (13) being located at a distance of 2 mm from the longer end of said plate (13) remote from the cylinder (1), and said cylinder (1) comprises an additional threaded bore (6) for inserting said screws (7), the two threaded bores (6) being located at right angles to said plate (12). According to the invention, there is preferred a system further comprising a closing cylinder (15) having a height equal to said lower of said heights and comprising a stem of round cross-section, and the top end of said closing cylinder (15) being a hemisphere (2) having a diameter of 0.5 mm less than the diameter of the cross-section of said closing cylinder (15); an axial circular bore (4) having a calibre of 2 mm, said axial circular bore (4) opening at the top and bottom ends of said closing cylinder (15) forming an internal duct, the top opening of said axial circular bore (4) being surrounded by four holes (5), said four holes (5) being arranged at the ends of a virtual cross, with connecting lines each being 4 mm long, and said top opening being at the intersection of said connecting lines; a flat lower end (16) for closing the system; a dihedral notch (38) along the length of its stem, said notch (18a) leading towards the central axis; and said axial circular bore (4) opens at the top end of said closing cylinder (15) and becomes said notch (38) in said stem of the closing cylinder (15). In a furthermore preferred system, (a) said braided wire (18) is a braided metal wire having a length of 40 cm and a thickness of 1.5 mm in order to pass freely through the axial circular bore (4) of said cylinders (1, 1a); (b) said braided wire (18) is fixed at a first end to a circular plate (9) having a diameter of 4 mm and shaped as a spherical shell, the surface of which being adjusted to the top surface of the cylinders (1, 1a); (c) said circular plate (9) comprises four spikes (19) each projecting, by a length of 1 mm, from the ends of two perpendicular diameters of said plate (9) so as to be housed in said four holes (5) surrounding said axial circular bore (4) at the top ends of said cylinders (1, 1a); and (d) said braided wire (18), at its second end ends in a point (20) allowing said braided wire (18) to be easily threaded through said axial circular bore (4) of the cylinders (1, 1a). One embodiment of the system of the invention is that the wire tightening means comprises a wrench having (a) a first part (21) being a metal cylinder having a length of 20 cm and a diameter of 1 cm, a first end of said first part (21) having two curved sheets (22) being sized so as to be able to firmly hold between them the closing cylinder (15); the first part having a bore (23) having a calibre of 2 mm being provided on the surface of said first part (21) at the midpoint between said two curved sheets (22), said bore (23) extending along the stem of said first part (21) to surface again (25) 2 cm from the second end of said first part (21); a cylindrical scoop at the surface of second end of said first part (21), said scoop extending along the central axis down to the first end; and the circular perimeter of the surface at the second end being a cog-wheel (28); and (b) the wrench having a second part (27) conformed as a hexagonal prism, having a stem (26) which can be housed in said cylinder scoop of the first part. Even more preferred is a wrench wherein said second part (27), which is conformed as a hexagonal prism has a major diameter of 6 mm and a length of 3 cm, a 2 mm bore (29) appearing at a distance of 5 mm from its first end and extending upwards inside said prism to surface again on the same face, 1 cm towards the second end. In an advantageous manner, the cylindrical stem (26), projecting from the first end of said prism (27) and fitting in the scoop provided therefor in the first, cylindrical part, crosses the full length of the first part, leaving through the first end of said first part (26a) and has a small boss that prevents vertical movement, thereby permanently fixing both first and second parts, and the second end of the prismatic part being a cog-wheel arranged to oppose the cogs on the first part. It is also particularly preferred that said system additionally comprises a T-shaped torque wrench (30) having a hexagonal pitch (31) adapted to the prism (27) on the second part and allowing the same to turn about the first part clockwise, the return motion being prevented by the cog-wheels (28) on both abutting parts. The system of the invention described above entails a number of advantages: Possibility of being used to join all the required levels; because it is jointed, neither the point of insertion of the screws nor the position of the hooks is predetermined, eliminating risks and expediting the placement and adaptation of the system to the morphology of the column; having screws and hooks, it can also be used after laminectomy. The system of the present invention affords the foregoing advantages, in addition to others that may be easily be inferred from the embodiment described in detail hereinafter to expedite the understanding of the characteristics set out before, contemporaneously revealing a number of details. For this purpose, this specification has attached a number of drawings showing, for illustrative and non-limitative purposes, a practical embodiment of its object. In the drawings, Figures 1 and 2 show a side elevation view of two segments of cylinders being large and small, respectively; Figures 3, 4 and 5 are cross-sections of the said segments, viewed along A-A', B-B' and C-C'; Figures 6, 7 and 8 show side elevation views of a type of cylinder having a downward hook; Figures 9, 10 and 11 show side elevation views of another type of cylinder having an upward hook; Figures 12, 13 and 14 show side elevation views of a third type of cylinder having a screw plate; Figure 15 illustrates a side elevation view of a closing cylinder; Figures 16 and 17 are cross-sections of the cylinder of the previous figure, seen along D-D' and E-E'; Figure 18 shows the articular screw; Figures 19 and 20 are the internal wire and a close view of the wire plate; Figures 21, 22 and 23 show the wire tightening wrench, seen separately as a front elevation of the top and lower part, a side elevation thereof and a plan view of the top part; Figure 24 is a longitudinal section of the lower part of the wire tightening wrench, seen along F-F'; Figures 25, 26, 27, 28, 29 and 30 are the various sections of the lower part of the wire tightening wrench, seen along G-G', H-H', I-I', J-J', K-K' and L-L'; and Figure 31 shows an embodiment of the assembled, stiffened and coupled system with the incurvations imposed by the setting elements. As shown in the drawings, the system for setting cervical vertebrae subject hereof, and in accordance with an embodiment thereof, comprises several distinct elements: The first group of elements comprises different parts, that we shall call segments or cylinders. Each of the segments is a solid metal cylinder 1 whose two ends are different. The top end is a hemisphere 2 having a diameter that is 0.5 millimetres shorter than the diameter of the cross-section of the cylinder. The lower end is scooped and forms a likewise hemispherical cavity 3 having an internal diameter that is 0.5 millimeters shorter than the diameter of the cylinder. The reason for having this shape and these dimensions at the ends is that the top protruding end of a cylinder can be precisely coupled to and turn within the lower scooped end of another cylinder arranged above the same. The whole cylinder is longitudinally crossed vertically by a hollow circular bore 4 having a 2 mm calibre, that opens at the top and bottom ends. This bore we shall refer to as cylinder web. At the top end, surrounding the top opening of the circular bore, there are four small holes 5 arranged at the ends of a cross whose lines are each 4 millimetres long. The holes are for the wire 8 plate 9 to be fitted. Halfway up the stem of the cylinder there is a threaded bore 6 with a 1.5 millimetre calibre, reaching the circular bore 4 or cylinder web. This bore shall house a small screw 7 whose blunt point shall, when fully screwed in, reach up to the opposite wall of the circular vertical bore of the cylinder. This is the screw that locks the wire 8. The cylinders are two in size: Large, as in Fig. 1, being e.g. 8 mm high, measured from the pole of the top hemisphere down to the perimeter of the hollow lower base, and being e.g. 5 mm in diameter. Small 1a, as in Fig. 2, being e.g. 4 mm high and 5 mm in diameter. The large cylinders are divided into four types: SIMPLE: Comprising a simple cylinder as described in Figures 1 to 5. WITH DOWNWARD HOOK: This is a "simple" cylinder with a hook 10 projecting from one of its sides. This hook shall comprise a 5 mm wide sheet projecting from the top half of the cylinder body, at an upwardly open 45° angle to the longitudinal axis of the cylinder. The sheet then bends down until its final portion is parallel to the longitudinal axis of the cylinder. In this type, the wire locking screw bore lies at the side of the cylinder being diametrically opposite the projection of the hook, as shown in Figures 6 to 8. WITH UPWARD HOOK: This is similar to the above, though in this case the hook 11 projects from the lower half of the cylinder at a downwardly open 45° angle and the sheet then bends up. In this type, the wire locking screw bore lies at the side of the cylinder being diametrically opposite the projection of the hook, as shown in Figures 9 to 11. WITH ARTICULAR SCREW PLATE 32: A trapezoidal vertical plate 12 projects from the cylinder body at the major axis plane of the cylinder, extending sideways for e.g. 15 mm. The shorter side of the plate has the same length as the cylinder stem. The longer side of the plate measures e.g. 8 mm. The plate is crossed at 2 mm from its free end, its longer end, by a hole 13 having a diameter of e.g. 3 mm. In this type, two bores 14 are provided for the wire locking screw, lying on both the front and the rear faces of the cylinder, relative to the plate, as shown in Figures 12 to 14. There are two types of small cylinders: SIMPLE: Carrying no hooks or plate, as in Fig. 2. CLOSING CYLINDER: This cylinder is numbered 15 and has a particular morphology. Its lower end is not scooped, and is flat instead as at 16. The stem 17 of the cylinder has a dihedral notch 38 along its length, leading towards the central axis. It carries no locking screw. The web, which opens at the top end, continues at the height of the cylindrical stem with the inner angle of the notch as in Figures 15 to 17. The second group of elements comprises the internal wire 8 and its components: The components are: A braided metal wire 18 being e.g. 40 cm long and e.g. 1.5 mm thick, being therefore able to pass freely through the circular bore 4 or hollow web of the segments. At one end the wire is fixed to a circular plate 9 having a diameter of e.g. 4 mm, and shaped as a spherical shell, the surface of which adjusts to the top end surface of the cylinder. This is the wire plate. Four spikes 19 being each e.g. 1 mm long, project from the ends of two perpendicular diameters of this plate, which shall be housed in the four bores 5 at the top end of the cylinder 1. The other end of the wire ends in a point 20 that allows the same to be easily threaded through the circular bore 4 or web of the segments. This is the wire point. The third element is the wire tightening wrench. Such comprises three parts, as in Figures 21 to 23. The lower part is a metal cylinder being e.g. 20 cm long and e.g. 1 cm in diameter. Its lower end has two curved sheets 22 being sized so as to be able to firmly couple between the same the closing cylinder. A 2 mm bore 23 is provided on the surface of the cylinder at the midpoint between these two sheets which extends upwards as at 24 along the stem of the cylinder to again surface at 25, 2 cm from the top end. The surface of the top end has a cylindrical scoop that extends along the central axis down to the lower end. This cavity houses the stem 26 of the top part 27. The circular perimeter of the top surface is a cog-wheel 28 with triangular rectangular cogs. The top part 27 is a hexagonal prism 27 with a major diameter of e.g. 6 mm and a length of e.g. 3 cm A 2 mm bore 29 appears at a distance of e.g. 5 mm from its lower end, extending upwards inside the prism 27 to surface again on the same face, e.g. 1 cm higher. A cylindrical stem, 26 projects from the lower end of the prism 27, which fits in the cavity provided therefor in the lower part, crossing its full length, leaving through the lower end of such part, as at 26a. At its outlet from the lower end of the lower part, the stem has a small boss that prevents vertical movement, thereby permanently fixing both parts. The lower end of the top part or prism 27 is a cog-wheel, with triangular rectangular cogs arranged inversely to the cogs on the lower part. A T shaped torque wrench 30 with a hexagonal pitch 31 adapting to the prism 27 on the top part and allowing to same to turn about the lower part clockwise. The return motion is prevented by the cog-wheels on both abutting parts. After exposing the rear arches of the vertebral segments that are to be merged, a decision is made as to the type of setting elements that are to be used for each level, hooks or screws, and the respective distances at which these elements shall have to be positioned are calculated. At the levels where screws 32 are to be used, these are placed directly on the articular masses, introducing the same to the limit and without any limitations as to their position. The various cylinders 1, 12, 15 having the required setting elements (upward facing hook 11, downward facing hook 10, screw plate 12) and the simple cylinders of different sizes are strung in the braided wire 8, 18. With the various sizes of simple cylinders 1, 1a the assembly shall be adjusted to the anatomic demands required by the vertebral morphology and size. The hooks are placed on the laminae and for the levels in which a screw 32 has been inserted, a cylinder and a plate 12 are placed. The projecting stem of the screw 32 is inserted through the bore in the plate 12 and the nut attaching the plate to the screw is then placed. As aforesaid, the distance between setting elements is covered with like elements. The last element strung in the wire is a closing cylinder 15. After the system is all assembled the central wire 8 is tightened using the appropriate wrench described in the apparatus section, and the system is thereby stiffened, adjusting to the incurvations imposed by the setting elements. Coupling is achieved due to the turning capacity the hemispherical arrangement at the top and lower ends of each cylinder provides. When the central wire is tightened to the limit, before removing the tightening wrench, the final position is consolidated by screwing the small screws 7 with which each cylinder is provided, compressing the wire in the central duct, preventing it from sliding. The tightening wrench is removed and forceps are used to tighten the closing cylinder 15 to the wire, solidly fixing the whole system. The closing cylinder 15 is coupled between the sheets 22 of the bottom end of the wrench 21. The tightening wire is placed in the dihedral notch 38 of the closing cylinder and is then inserted through the lower bore of the lower part until it leaves through the top bore. The wire is then inserted through the lower bore of the top part until it leaves through the top bore. At this point, the torque wrench is used to turn the top part about the lower part, in such a way that the free end of the wire is wound around the prism and is tightened until the torque wrench stops turning. The tension applied to the wire is preserved because the two cog-wheels at the top and bottom ends of the two parts prevent a turn in the direction opposite the direction in which force is applied. With the wrench in position, the locking screws in each cylinder are gradually tightened, starting with the top cylinder and moving down towards the bottom cylinder. After tightening each locking screw it is found that the torque wrench cannot turn, viz. it is found that the wire has lost no tightness. Once all the locking screws are tightened, the tightening wrench is removed and suitable forceps are used to tighten the closing cylinder 15 in order for the dihedral notch 38 to close upon the wire 8,18 preventing it from slipping or becoming loose.

Claims: A system for setting cervical vertebrae from behind, characterized in comprising (a) a group of distinct solid metal cylinders (1, 1a), said cylinders (1, 1a) having a stem of round cross-section and one of two possible heights, the top end of said cyclinders (1, 1a) being a hemisphere (2) having a diameter of 0.5 mm less than the diameter of the cross-section of said cylinders (1, 1a), whereas the lower end of said cylinders (1, 1a) is scooped to form a hemispherical cavity (3) whose internal diameter is 0.5 mm less than that of the cross-section of said cylinders (1, 1a) in order that the top protruding end (2) of one of said cylinders (1, 1a) may be precisely coupled to and turn within the lower scooped end (3) of another of said cylinders (1, 1a); (b) said cylinders (1, 1a) having an axial circular bore (4) having a calibre of 2 mm, said axial circular bore (4) opening at the top and bottom ends of said cylinders (1, 1a) forming an internal duct, the top opening of said axial circular bore (4) being surrounded by four holes (5), said four holes (5) being arranged at the ends of a virtual cross, with connecting lines each being 4 mm long, and said top opening being at the intersection of said connecting lines; and (c) the cylinder stem having at its longitudinal midpoint a threaded bore (6) with a calibre of 1.5 mm, said threaded bore (6) reaching the internal duct, said duct in the cylinders (1, 1a) allowing a number of said cylinders (1, 1a) to be strung by means of a braided wire (18), to form a structural assembly suited to the anatomic demands of the patient's vertebral morphology and size, the assembly being capable of being stiffened by tightening the said wire (18) using a wire tightening means, which couples the top and bottom ends of each of said cylinders (1, 1a); (d) the final structure of the assembly being consolidated by setting each of said cylinders (1, 1a) one by one onto said wire (18), using small screws (7) inserted in the said threaded bore (6) provided in the stem of each of said cylinders (1, 1a), said screws (7) compressing the wire (18) in the internal duct, thereby preventing said cylinders (1, 1a) from slipping. The system as in claim 1, wherein one of said cylinders (1) having the larger height is 8 mm high, measured from the top end of said hemisphere (2) to the perimeter of said hemispheral cavity (3), and has a diameter of 5 mm, whereas another of said cylinders (1a) having the lower height is 4 mm high and has a diameter of 5 mm. The system as in claim 1 or claim 2, wherein one of said cylinders (1) having the larger height is a cylinder selected from (a) one of said cylinders (1); (b) one of said cylinders (1), additionally comprising a downward hook (10) projecting from the upper half of a side wall of the cylinder body at an upwardly open 45 ° angle to the longitudinal axis of the cylinder (1) and bending down until its final portion is parallel to the longitudinal axis of said cylinder (1); (c) one of said cylinders (1), additionally comprising an upward hook (11) projecting from the lower half of a side wall of the cylinder body at a downwardly open 45 ° angle to the longitudinal axis of the cylinder (1) and bending up until its final portion is parallel to the longitudinal axis of said cylinder (1); and (d) one of said cylinders (1), additionally comprising an articular screw plate (12) of trapeziodal shape projecting from a side wall of the cylinder body at the major axis plane of the cylinder (1) with a length of 15 mm and having the same heigth as the cylinder stem on the side adjacent to the cylinder (1) and a heigth of 8 mm on the side remote from the cylinder (1). The system as in claim 3, wherein the cylinder (1) having a downward hook (10) comprises the hook (10) as a 5 mm wide strip, and said threaded bore (6) for inserting said screws (7) is located on the side of said cylinder (1) diametrically opposite to the side from which the hook (10) projects. The system as in claim 3, wherein the cylinder (1) having an upward hook (11) comprises the hook (11) as a 5 mm wide strip, and said threaded bore (6) for inserting said screws (7) is located on the side of said cylinder (1) diametrically opposite to the side from which the hook (11) projects. The system as in claim 3, wherein the cylinder (1) having an articular screw plate (12) has said plate (12) pierced by a hole (13) having a diameter of 3 mm, said hole (13) being located at a distance of 2 mm from the longer end of said plate (13) remote from the cylinder (1), and said cylinder (1) comprises an additional threaded bore (6) for inserting said screws (7), the two threaded bores (6) being located at right angles to said plate (12). The system as in claims 1 to 6, further comprising a closing cylinder (15) having a height equal to said lower of said heights and comprising a stem of round cross-section, and the top end of said closing cylinder (15) being a hemisphere (2) having a diameter of 0.5 mm less than the diameter of the cross-section of said closing cylinder (15); an axial circular bore (4) having a calibre of 2 mm, said axial circular bore (4) opening at the top and bottom ends of said closing cylinder (15) forming an internal duct, the top opening of said axial circular bore (4) being surrounded by four holes (5), said four holes (5) being arranged at the ends of a virtual cross, with connecting lines each being 4 mm long, and said top opening being at the intersection of said connecting lines; a flat lower end (16) for closing the system; a dihedral notch (38) along the length of its stem, said notch (18a) leading towards the central axis; and said axial circular bore (4) opens at the top end of said closing cylinder (15) and becomes said notch (38) in said stem of the closing cylinder (15). The system as in claims 1 to 7, wherein (a) said braided wire (18) is a braided metal wire having a length of 40 cm and a thickness of 1.5 mm in order to pass freely through the axial circular bore (4) of said cylinders (1, 1a); (b) said braided wire (18) is fixed at a first end to a circular plate (9) having a diameter of 4 mm and shaped as a spherical shell, the surface of which being adjusted to the top surface of the cylinders (1, 1a); (c) said circular plate (9) comprises four spikes (19) each projecting, by a length of 1 mm, from the ends of two perpendicular diameters of said plate (9) so as to be housed in said four holes (5) surrounding said axial circular bore (4) at the top ends of said cylinders (1, 1a); and (d) said braided wire (18), at its second end ends in a point (20) allowing said braided wire (18) to be easily threaded through said axial circular bore (4) of the cylinders (1, 1a). The system as in claim 7, wherein the wire tightening means comprises a wrench having (a) a first part (21) being a metal cylinder having a length of 20 cm and a diameter of 1 cm, a first end of said first part (21) having two curved sheets (22) being sized so as to be able to firmly hold between them the closing cylinder (15); the first part having a bore (23) having a calibre of 2 mm being provided on the surface of said first part (21) at the midpoint between said two curved sheets (22), said bore (23) extending along the stem of said first part (21) to surface again (25) 2 cm from the second end of said first part (21); a cylindrical scoop at the surface of second end of said first part (21), said scoop extending along the central axis down to the first end; and the circular perimeter of the surface at the second end being a cog-wheel (28); and (b) the wrench having a second part (27) conformed as a hexagonal prism, having a stem (26) which can be housed in said cylinder scoop of the first part. The system as in claim 9, wherein said second part (27), which is conformed as a hexagonal prism has a major diameter of 6 mm and a length of 3 cm, a 2 mm bore (29) appearing at a distance of 5 mm from its first end and extending upwards inside said prism to surface again on the same face, 1 cm towards the second end. The system as in claim 9 or claim 10, wherein the cylindrical stem (26), projecting from the first end of said prism (27) and fitting in the scoop provided therefor in the first, cylindrical part, crosses the full length of the first part, leaving through the first end of said first part (26a) and has a small boss that prevents vertical movement, thereby permanently fixing both first and second parts, and the second end of the prismatic part being a cog-wheel arranged to oppose the cogs on the first part. The system as in claims 9 or 10, said system additionally comprising a T-shaped torque wrench (30) having a hexagonal pitch (31) adapted to the prism (27) on the second part and allowing the same to turn about the first part clockwise, the return motion being prevented by the cog-wheels (28) on both abutting parts.

Inventors: BARBERA ALACREU JOSE VICENTE, BARBERA ALACREU, JOSE VICENTE, Barbera Alacreu, José Vicente
Applicants: BARBERA ALACREU JOSE VICENTE, BARBERA ALACREU, JOSE VICENTE
Application year: 1994
Main classification: A61B17
IPC codes: A61B17